Oil light dimly lit.

[Narcisist]

So I got stuck at work the other day a little late and it got dark, I was riding home and noticed that my oil light was glowing a little bit, not enough that I can tell in the day time, so I don't know how long it's been doing it. It got brighter as the rpms went up, but then it would just shut off before starting to glow dimly again. The oil is full, mobil 1 15w50. It is pretty cold around here, 30-40 degree range. Any ideas what the problem could be? I work on cars all the time, but I'm a little leary about tearing into a motorcycle without getting all the ideas that I can. Thanks alot.

[BigDick]

when you turn your ignition on with the motor not running does the light come on brightly or is it the same dim glow?

[Narcisist]

It's bright when I turn the ignition on, before I start. Goes off when I start, and then comes on real dim as I drive away.

[BigDick]

Just guessing here but I would say it's nothing to worry about. Mine does the same. It could be glow from your speedo illumination "bleeding across" through the red lens.

[The Lorax]

check your brake and tail lights, that particular light gives indication of oil pressure (lack there of) tail light illumination, and brake light illumination. if the label on your pilot box isn't completely worn off (as mine is) it should say " tail/brake/oil" or something like that. just a thought, it appears as though your oil pressure switch it working as it is bright when you turn it on but goes out when you start it. just to be safe, ensure you have good pressure, but it might be a light issue also. have a nice day and ride safe

[Narcisist]

How exactly do you check to make sure you're getting good oil pressure?

[The Lorax]

you know, I thought about that after I typed it, I don't have a good answer for that. the pressure switch is a go - no go if I remember correctly, you could put an volt meter on the switch and start the bike and watch to see it go from zero to whatever voltage it goes to (probably 12 but some stuff runs off a slightly lower voltage). you could get a pressure gauge and put it in in place of the pressure switch although while it's in there the red light will be on bright. perhaps someone on the forum will know a better way. I still think your issue is probably brake light or tail light related, but it never hurts to be sure. have a nice day and ride safe

[cywelchjr]

you know, I thought about that after I typed it, I don't have a good answer for that. the pressure switch is a go - no go if I remember correctly, you could put an volt meter on the switch and start the bike and watch to see it go from zero to whatever voltage it goes to (probably 12 but some stuff runs off a slightly lower voltage). you could get a pressure gauge and put it in in place of the pressure switch although while it's in there the red light will be on bright. perhaps someone on the forum will know a better way. I still think your issue is probably brake light or tail light related, but it never hurts to be sure. have a nice day and ride safe

Actually I think that if you took it out to put a guage in there the light would not come on at all as I believe it is the ground for the light, and opens to turn it off.

[Narcisist]

So I run it for a quick test spin to check your theory, and sure enough. . .The light gets brighter with higher rpms, but shuts off the second you touch the front brake lever. I did recently rebuild the mc, and installed stainless lines. I did it all just by doing it, without any manual's and such so maybe I got something off when I put the master cylinder back together? What do you think?

[The Lorax]

Could very well be, there is a switch for the brake light on the assembly, possibly there's a resistive short somewhere around the switch, and the current flow is just enough for the circuit to think the brake is being depressed and no light or something like that, I don't know the circuit all that well but as soon as you pull the lever, the current flow is there and the light goes out. it gives you something to look at anyway, good place to start. have a nice day and ride safe

[Ivan]

To check oil pressure, you take the switch out and attach a hose with the correct fitting that has a gauge on the other end.

I will second the brake and tail light theory. Especially if you have some corrosion in one of the sockets.

[oldyam80sg]

When you remove the switch from the handlebars be careful as it has a plastic tang to hold it in place.If that breaks the light wont work and you wont have brake lights.I have a replacement switch available if needed.

[Narcisist]

So now that I've identified the problem as having something to do with the front brakes, the problem evolved on me and now the light is on bright unless I'm holding the lever down at a light. Now, I can rebuild an engine, take apart carbs, but electricity is a foreign concept to me. I have no ideas at all how to fix it. Please help? . .

[The Lorax]

Carefully remove the switch from the front brake, and inspect it for debris or dirt or carbon or any of that stuff as any can partially complete the circuit and possibly give the "warning light". I know, I don't use the best nomenclature in the world but I think I get the general point across. basically the switch might be dirty and have some crap in it or other debris it picked up, check the wiring in that vicinity as well, look for worn insulation and stuff like that. electronics is not to difficult to figure out. I have virtually no education in the field and yet I make a living working with it (albeit high voltage electronics, but electronic is electronics, it just hurts more when you dealing with kilo volts as opposed to volts...then there's that whole burnt flesh thing.....) anyway, you can do it, just take your time and go through it one piece at a time. have a nice day and ride safe

[bikerphil]

The 79 Specials use a light checker unit that is near the battery. My oil light would come on erratically, and i finally traced it to that unit. If I'd jiggle the wires coming out of it, the problem went away. I ended up twisting the wires and that cleared it up, at least for now. It's been fine for 2 yrs. or so.